19-5262; Rev 0; 11/11
MAX5974C Evaluation Kit
Evaluates: MAX5974C
General Description
The MAX5974C evaluation kit (EV kit) is a fully assembled
and tested surface-mount circuit board featuring the
MAX5974C active-clamped, spread-spectrum, current-
mode PWM controller for Power-over-Ethernet (PoE)
powered device (PD) applications. The EV kit is a
compact and low-cost design used in power-over-
LAN (PoLAN) applications requiring DC power from an
Ethernet network port for PDs such as IP phones, wire-
less access nodes, and security cameras.
The EV kit features a galvanically isolated 25W, 250kHz
switching-frequency, active-clamped, synchronous-rec-
tified forward DC-DC converter using the IC. The device
circuit achieves high efficiency up to 93.5% using a
forward DC-DC converter topology. The surface-mount
transformer provides up to +1500V galvanic isolation for
the output. The EV kit output voltage is configured for
+5V and provides up to 4.7A load current.
The EV kit includes the MAX5969B IEEE
M
802.3af/at-
compliant network PD interface controller IC, which pro-
vides PD detection signature, PD classification signature,
inrush current control, and undervoltage lockout (UVLO).
The EV kit circuit receives its power from IEEE 802.3af/
at-compliant power-sourcing equipment (PSE). The PSE
provides the required -39V to -57V DC power over an
unshielded twisted-pair Ethernet network cable to the
EV kit’s RJ45 MagJack
M
. The EV kit features a 1 x 1Gb
RJ45 MagJack and two full-bridge diodes for separat-
ing the DC power provided by an endspan or midspan
Ethernet system.
The EV kit circuit can also be powered by a +37V to
+57V wall adapter power source, applied at the PWR+
and PWR- PCB pads. When a wall adapter power source
is detected, it always takes precedence over the PSE
source, allowing the wall adapter to power the EV kit.
Warning:
The EV kit is designed to operate with high
voltages. Dangerous voltages are present on this EV kit
and on equipment connected to it. Users who power up
this EV kit or power the sources connected to it must be
careful to follow safety procedures appropriately to work
with high-voltage electrical equipment.
Under severe fault or failure conditions, this EV kit may
dissipate large amounts of power, which could result in
the mechanical ejection of a component or of component
debris at high velocity. Operate this kit with care to avoid
possible personal injury.
Features
S
IEEE 802.3af/at-Compliant PD Interface Circuit
S
-39V to -57V Startup Input Voltage Range
S
Demonstrates an Isolated 25W Active-Clamped,
Synchronous-Rectified Forward DC-DC Converter
S
Demonstrates Up to 93.5% Efficiency
S
Isolated +5V Output at 4.7A
S
PD Detection and Configurable Classification
Signatures
S
Inrush Current Limit of 180mA (max)
S
2-Event Classification or Wall Adapter Detect
Output
S
Internal UVLO at +38V
S
Evaluates Endspan and Midspan Ethernet
Systems
S
Simplified Wall Adapter Interface
S
Proven PCB Layout
S
Fully Assembled and Tested
Ordering Information
appears at end of data sheet.
EFFICIENCY vs. OUTPUT CURRENT
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
1
2
3
4
5
OUTPUT CURRENT(A)
V
IN
= 57V
V
IN
= 48V
V
IN
= 42V
Figure 1. MAX5974C EV Kit Efficiency vs. Output Current at
V
IN
= 42V, 48V, and 57V
IEEE is a registered service mark of the Institute of Electrical
and Electronics Engineers, Inc.
MagJack is a registered trademark of Bel Fuse Inc.
_________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX5974C Evaluation Kit
Evaluates: MAX5974C
Component List
DESIGNATION
C1, C6
QTY
2
DESCRIPTION
1FF
Q10%,
100V X7R ceramic
capacitors (1210)
AVX 12101C105KAT9A
0.1FF
Q10%,
100V X7R ceramic
capacitor (0805)
TDK C2012X7R2A104K
0.056FF
Q10%,
16V X7R
ceramic capacitor (0402)
Murata GRM155R61C563K
22FF
Q10%,
25V X7R ceramic
capacitor (1210)
Murata GRM32ER61E226K
0.047FF
Q10%,
50V X7R
ceramic capacitor (0603)
Murata GRM188R71H473K
33FF
Q20%,
63V aluminum
electrolytic capacitor
(8.3mm x 8.3mm)
Panasonic EEE1JA330P
100FF
Q20%,
6.3V X5R ceramic
capacitors (1210)
TDK C3225X5R0J107M
22FF
Q10%,
10V X7R ceramic
capacitor (1210)
Murata GRM32ER71A226K
Not installed, ceramic capacitor
(1210)
0.1FF
Q10%,
50V X7R ceramic
capacitor (0603)
Murata GRM188R71H104K
0.1FF
Q10%,
100V X7S ceramic
capacitor (0603)
TDK C1608X7S2A104K
0.01FF
Q10%,
10V X5R ceramic
capacitor (0402)
Murata GRM155R61A103K
1FF
Q10%,
10V X5R ceramic
capacitor (0402)
Murata GRM155R61A105K
Not installed ceramic capacitors
(0402)
4700pF
Q10%,
250V X7R
ceramic capacitor (1206)
AVX 1206PC472KAT1A
DESIGNATION
C18
QTY
1
DESCRIPTION
2200pF
Q20%,
250VAC X7R
ceramic capacitor (2220)
Murata GA355QR7GF222KW
6800pF
Q10%,
25V X7R ceramic
capacitor (0402)
Murata GRM155R71E682K
0.1FF
Q10%,
16V ceramic
capacitor (0402)
Murata GRM155R71C104K
1000pF
Q10%,
1500V X7R
ceramic capacitor (1210)
AVX 1210SC102KATA
330pF
Q10%,
50V X7R ceramic
capacitor (0402)
Murata GRM155R71H331K
0.015FF
Q10%,
25V ceramic
capacitor (0402)
TDK C1005X7R1E153K
200V, 1A bridge rectifier diodes
(Mini-DIP)
Diodes Inc. HD01-T
600W, 58V TVS diode (SMB)
Diode Inc. SMBJ58A
100mA, 80V diodes (SOD323)
Diodes Inc. 1N4148WS
22V zener diode (SOD123)
Fairchild MMSZ5251B
100V, 2A Schottky diode (SMB)
Diodes Inc. B2100-13-F
200mA, 200V diodes (S-Mini2)
Panasonic DA2J108
Modular side-entry, 8-position
jack assembly
3300FH, 0.024A inductor
Coilcraft LPS4018-335ML
6.8FH, 8.5A inductor
Pulse PG0702.682NL
3.3FH, 2.6A inductor
Cooper Bussmann SD53-3R3-R
25V, 58A n-channel MOSFETs
(PowerPak 8 SO)
Infineon BSC050NE2LS
-150V, -0.42A p-channel
transistor (6 SC70)
Vishay Si1411DH
C2
1
C19
1
C3
1
C21
1
C4
1
C22
1
C5
1
C24
1
C7
1
C25
1
D1, D2
2
C8, C9
2
D3
D4, D5, D8, D10
D6
D7
D9, D11
J1
L1
L2
L3
1
4
1
1
2
1
1
1
1
C10
1
C11
0
C12
1
C13
1
C14
1
C15
C16, C20, C23,
C26
C17
1
0
N1, N2
2
1
N4
1
_________________________________________________________________
Maxim Integrated Products
2
MAX5974C Evaluation Kit
Evaluates: MAX5974C
Component List (continued)
DESIGNATION
N5
PGND, +5V
Q1
Q2
R1
R2, R17, R47
R4
R5
R6
R7
R8
R9
R10
R12, R13
R14
R15
R16
R18
R19, R23
R20
R21, R25
R26, R48
R27
R28
R29
R30
R31
R32
R33
R34
QTY
1
2
0
0
1
0
1
1
1
1
1
1
1
2
1
1
1
1
2
1
2
2
1
1
1
1
1
1
1
1
DESCRIPTION
150V, 2.3A n-channel transistor
(6 SuperSOT)
Fairchild FDC86244
Uninsulated banana jacks
Not installed, npn transistor
(SOT23)
Not installed, pnp transistor
(SOT23)
30.1kI
Q1%
resistor (0603)
Not installed, resistors (0402)
30.9I
Q1%
resistor (0805)
59kI
Q5%
resistor (0603)
16.9kI
Q1%
resistor (0402)
34kI
Q1%
resistor (0402)
1.5MI
Q1%
resistor (0603)
100kI
Q5%
resistor (0402)
2kI
Q1%
resistor (0402)
10I
Q5%
resistors (0805)
24.9kI
Q1%
resistor (0603)
34.8kI
Q1%
resistor (0402)
0I
Q5%
resistor (0402)
499I
Q1%
resistor (0402)
10I
Q5%
resistors (0603)
10kI
Q1%
resistor (0603)
0.4I
Q1%,
1/2 W resistors (1206)
IRC LRC-LRF-1206LF-01-R400-F
100I
Q1%
resistors (0402)
100kI
Q1%
resistor (0402)
36.5kI
Q1%
resistor (0402)
162kI
Q1%
resistor (0402)
121kI
Q1%
resistor (0402)
4.99kI
Q1%
resistor (0402)
1kI
Q1%
resistor (0402)
1kI
Q1%
resistor (0402)
4.02kI
Q1%
resistor (0402)
U4
—
1
1
U3
1
U2
1
U1
1
T1
1
TPGND
TP5V
1
1
RJ45
1
DESIGNATION
R35
R36
R37
R38, R39, R44,
R45
R40, R41, R42,
R43
R46
QTY
1
1
1
0
4
1
DESCRIPTION
7.5kI
Q1%
resistor (0402)
2.49kI
Q1%
resistor (0402)
1MI
Q5%
resistor (0402)
Not installed, resistors (0603)
75I
Q5%
resistors (0603)
0I
Q5%
resistor (0603)
RJ45 MagJack 1G-Ethernet,
802.3af/at standard
Bel Fuse Inc. 0826-1X1T-GH-F
Black test point
Red test point
0.50:0.25:0.25:1 forward
transformer (10 EP13)
Cooper Bussmann
CTX03-18842-R
Active-clamped PWM controller
(16 TQFN-EP)
Maxim MAX5974CETE+
(Top Mark: AIA)
IEEE802.3at-compliant powered
device (10 TDFN-EP )
Maxim MAX5969BETB+
(Top Mark: AWP)
70V, 200% to 400% CTR
phototransistor
(4 DIP, surface mount)
Fairchild FOD817CSD
(Top Mark: TAI_)
1.24V shunt regulator (5 SOT23)
PCB: MAX5974C EVALUATION
KIT
_________________________________________________________________
Maxim Integrated Products
3
MAX5974C Evaluation Kit
Evaluates: MAX5974C
Component Suppliers
SUPPLIER
AVX Corporation
Bel Fuse Inc.
Coilcraft, Inc.
Cooper Bussmann
Diodes Incorporated
Fairchild Semiconductor
Infineon Technologies AG
IRC Inc.
Murata Electronics North America, Inc.
Panasonic Corp.
Pulse Engineering
TDK Corp.
Vishay
PHONE
843-946-0238
201-432-0463
847-639-6400
916-941-1117
805-446-4800
888-522-5372
919-998-5334
361-992-7900
770-436-1300
800-344-2112
858-674-8100
847-803-6100
402-563-6866
WEBSITE
www.avxcorp.com
www.belfuse.com
www.coilcraft.com
www.cooperet.com
www.diodes.com
www.fairchildsemi.com
www.infineon.com
www.irctt.com
www.murata-northamerica.com
www.panasonic.com
www.pulseeng.com
www.component.tdk.com
www.vishay.com
Note:
Indicate that you are using the MAX5974C when contacting these component suppliers.
Quick Start
• MAX5974C EV kit
Detailed Description of Hardware
The MAX5974C EV kit is a fully assembled and tested
surface-mount circuit board that evaluates the MAX5974C
active-clamped, current-mode PWM controller. The EV kit
features a powered Ethernet port, a data-only Ethernet
port, and a MAX5969B IEEE 802.3af/at-compliant net-
work PD interface-controller IC.
The EV kit is a galvanically isolated 25W DC-DC con-
verter using the active-clamped, current-mode PWM
controller IC in a forward-feedback topology. The EV
kit receives power from an IEEE 802.3af/at-compliant
PSE and a UTP cable connected to the EV kit’s RJ45
MagJack. The EV kit uses a 1 x 1Gb RJ45 MagJack and
two diode-bridge power rectifiers (D1, D2) to separate
the -57V DC power sent by the PSE. The EV kit accepts
power from an endspan or midspan PSE network con-
figuration. The EV kit also provides Ethernet jack J1 for
interfacing to the Ethernet data signals. PCB pads VDD
and VSS are available for powering the EV kit, if network
connectivity is not required.
The EV kit output voltage is configured for +5V and
provides up to 4.7A output current. The EV kit circuit
achieves up to 93.5% efficiency using MOSFETs N1
and N2 for synchronous rectification on the secondary
side. Transformer T1 provides up to 1500V galvanic
isolation for the output. Isolated feedback voltage is
achieved using optical coupler U3 and voltage regulator
U4. Current-sense resistors R21 and R25 limit the peak
current through transistor N5 and primary transformer T1.
Capacitor C17 and transistor N4 form a clamping net-
work that protects transformer T1 against saturation due
to reverse current, by monitoring the voltage across the
IC’s CS input during auxiliary driver N4 off-time.
Required Equipment
• IEEE 802.3af/at-compliant PSE and Category 5e
Ethernet network cable
• -48V, 1A-capable DC power supply
• Voltmeter
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation.
Caution: Do not turn on
the power supply until all connections are completed.
1) Use one of the following methods to power the EV kit:
•
If network connectivity is required:
Connect a
Category 5e Ethernet network cable from the EV
kit input port RJ45 MagJack connector (RJ45) to
the corresponding PSE Ethernet LAN connection,
which provides power to the EV kit. Ethernet jack J1
provides an interface with the Ethernet data signals
only.
•
If network connectivity is not required:
Connect
a -48V DC power supply between the VDD and
VSS PCB pads on the EV kit. Connect the power-
supply positive terminal to the VDD pad and the
negative terminal to the VSS PCB pad.
2) Activate the PSE power supply or turn on the external
DC power supply.
3) Using a voltmeter, verify that the EV kit provides +5V
across the +5V and PGND PCB pads.
PGND is gal-
vanically isolated from the EV kit’s input VDD and
VSS PCB pads.
Hardware Connections
_________________________________________________________________
Maxim Integrated Products
4
MAX5974C Evaluation Kit
Evaluates: MAX5974C
The EV kit also demonstrates the full PD functionality of
the MAX5969B (U2), such as PD detection signature,
PD classification signature, inrush current control, and
UVLO. Resistors R14 and R4 set the PD detection sig-
nature and the PD classification signature, respectively.
The EV kit circuit accepts power from a wall adapter
DC power source. When a wall adapter power source
in the +37V to +57V range is applied at the PWR+ and
PWR- PCB pads, it always takes precedence over the
PSE source, allowing the wall adapter to power the EV kit
circuit. When applying a valid voltage source between
the PWR+ and PWR- PCB pads, the MAX5969B internal
isolation switch disconnects VSS from RTN, which allows
the wall adapter to supply power to the EV kit.
The EV kit is configured for a Class 4 (12.95W to 25.5W)
PD classification by resistor R4. To reconfigure the PD
classification, replace surface-mount 0805 resistor R4.
Table 1 lists the PD classification options.
The EV kit can also accept power from a wall adapter
DC power source, applied at the PWR+ and PWR- PCB
pads. The wall adapter power-source operating-voltage
range must be within +37V to +57V for the EV kit.
When the wall adapter power source is above +33.6V it
takes precedence over the PSE source. Once the wall
adapter power source is detected, the MAX5969B inter-
nal isolation switch disconnects VSS from RTN. The wall
adapter power is supplied to VDD (through diode D7)
and RTN. Once it takes over, the classification process
is disabled. Resistors R27 and R28 are available for
adjusting the EV kit wall adapter voltage for disabling the
PSE source.
When the wall adapter power source is below +27V the
PSE provides power through the RTN pin on U2. Diode
D7 prevents the PSE from backdriving the wall adapter
power source when it is below +7V.
The EV kit features Ethernet jack J1 to interface with the
Ethernet data signals. J1 is provided for interfacing the EV
kit with the Ethernet data signals only. Refer to the RJ45
MagJack data sheet on the Bel Fuse website prior to inter-
facing the EV kit’s J1 jack with the Ethernet data signals.
PD Classification Signature
Ethernet Data-Signal Interfacing
Wall Adapter Power Source (PWR+, PWR-)
Table 1. PD Classification Signature
Selection
CLASS
0
1
2
3
4
5
Maximum Power Used
by PD (W)
0.44 to 12.95
0.44 to 3.84
3.84 to 6.49
6.49 to 12.95
12.95 to 25.5
> 25.5
Resistor
R4 (I)
615
117
66.5
43.7
30.9
21.3
_________________________________________________________________
Maxim Integrated Products
5
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